Documents of many types are susceptible to tampering, alteration and counterfeiting. One example is a lottery ticket for a probability game. A probability game lottery ticket normally has play areas, each containing play indicia covered by an opaque material, for example a latex material. To play the game, an individual scratches off the latex covering a specified number of the play areas to reveal the play indicia underneath. The player then determines if the combination of revealed play indicia is a winner such as the play indicia are all the same symbol or add up to a winning number.
Part of the popularity of such probability games is derived from the fact that each and every ticket is a potential winner. If a player has lost, the player can scratch off the latex covering the remaining play areas and verify that at least one winning combination is present. Consequently, this type of game is generally perceived by lottery players as being more legitimate than other types of instant lottery games.
The fact that every ticket is potentially a winner also invites players to tamper with the tickets. Because every ticket can win if the right play areas are selected, some players look for ways to determine the play indicia contained in every play area in order to identify the location of a winning combination. If the player can conceal the fact that he has seen the play indicia, the player subsequently can remove the latex covering from the play areas containing the winning combination and claim a prize.
One technique used to accomplish this result involves lifting the latex to look at the play indicia before gluing the latex back into place. Typically, probability game lottery tickets are validated by the visual observation of a human lottery agent. It can be difficult to visually detect this sort of tampering. Thus, probability game lottery tickets are susceptible to fraudulent tampering.
A second threat to the integrity of a document is the intentional alteration of its contents. For example, an individual may try to alter the information on a driver's license, contract, test answer form, invoice or inventory form. Such an alteration may involve the changing of a number in the document by removing the original number and inserting a new number. In many cases alterations can be very difficult to detect, especially if there are no other copies of the document.
A third type of problem posed in the document security context involves counterfeiting. Rather than altering an existing document, the counterfeiter actually creates a document and attempts to pass it off as being genuine. Thus, paper currency, tickets, tags, and labels are often counterfeited and proffered as the real thing. The magnitude of this problem has substantially increased with the advent of the color photo copier.
For example, the owner of a trademark might sell t-shirts bearing that trademark to increase the value of the shirt. In an attempt to thwart pirates, the trademark owner might also attach a identifying tag to the t-shirts. This makes it easier to determine whether a given t-shirt is genuine. In order to disguise the fact that t-shirts are counterfeits, a counterfeiter will reproduce not only the t-shirt's design, but also the tag. While being forced to create a similar looking tag will increase his costs, if the value of the trademark is sufficentely high, the counterfeiter will continue to attach a counterfeited tag.
Hence, it is desirable to provide a system for verifying and validating documents to discourage tampering, alteration and counterfeiting.